核主泵屏蔽套用薄板激光焊接应力和变形的多场协同调控数值模拟

Numerical Simulation of Multi-field Coordinated Control of Stresses and Distortions in Laser Welding of Thin Sheet for Nuclear Reactor Coolant Pump Can

为了揭示核主泵屏蔽套用Hastelloy C-276薄板脉冲激光焊接的热力学行为,借助ANSYS软件建立了三维有限元模型。实验测量了焊接温度历程和残余变形,验证了所建立有限元模型的可靠性。基于验证的有限元模型,采用改变焊接过程中的夹具拘束和随焊激冷等多场调控参数的方法,进一步研究了夹具拘束距离、激冷位置以及激冷强度对Hastelloy C-276薄板焊接纵向残余应力和横向收缩变形的影响规律。结果表明,温度历程和残余变形的模拟结果与实验结果吻合较好;多场调控参数对焊接纵向残余应力和横向收缩变形的分布和大小有显著影响。鉴于焊接纵向残余应力和横向收缩变形是影响核主泵屏蔽套周长尺寸精度、整体稳定性以及超长使役的关键因素,确定了既降低横向收缩变形又兼顾纵向残余应力尽量小的合理多场调控参数是夹具拘束距离为12 mm,激冷位置为6 mm以及激冷强度为12500 W/(m^2·K)。

A three-dimensional finite element model(FEM)was developed by using ANSYS software to reveal the thermal-mechanical behaviors during the pulsed laser welding(PLW)of Hastelloy C-276 thin sheet for nuclear reactor coolant pump can.The welding temperature histories and residual distortions were measured to validate the FEM.Based on the verified FEM,the effects of the restraint distance,cooling position and cooling intensity on the longitudinal residual stress and transverse shrinkage distortion of Hastelloy C-276 thin sheet were investigated by the method of changing the multi-field coordinated control parameters of the fixture restraint and trailing heat sink.The results show that the simulated temperature histories and residual distortions agree well with the experimental results;the multi-field coordinated control parameters has a great influence on the distribution and magnitude of the longitudinal residual stress and transverse shrinkage distortion.As the longitudinal residual stress and transverse shrinkage distortion are the key factors for affecting the circumference dimension precision,overall stability and overlength service of the nuclear reactor coolant pump can,the reasonable multi-field coordinated control parameters for reducing the transverse shrinkage distortion and the longitudinal residual stress as small as possible were the restraint distance of 12 mm,the cooling position of 6 mm and the cooling intensity of 12500 W/(m^2·K).